Isotope ratio (IR) mass spectrometry (MS) (i.e., IRMS), and laser ablation (LA) mass spectrometry (MS) (i.e., LAMS) are conventional approaches for detecting isotopes. These systems typically involve converting laser ablated material into carbon dioxide or carbon monoxide, which species are then measured with a mass spectrometer to provide an isotope ratio for analytes of interest. Tunable IR laser absorption spectroscopies can measure raw isotopic differences for many different gaseous samples at precisions better than 0.2‰. And, they can offer a natural means to avoid isobaric interferences (14N14N16O, 16O12C16O, and etc.) because the IR absorption transitions are quite specific to molecular structure. In fact, even pure isomers including rearrangement isotopologues such as 14N15NO and 15N14NO, etc. can be readily distinguished with tunable IR laser absorption spectroscopy. Laser-based isotope discriminators are also being developed to handle a variety of gaseous compounds since much less sample preparation is needed to isolate isobaric interferences. And, laser-based systems and methods can offer more flexibility in performing real-time or near real-time isotopic analyses of atmospheric gas samples in the field with direct ingestion of mixed gas samples. However, most commercial laser absorption-based devices are designed for fast in situ analyses of ambient gases. And, with long path-length absorption cells, such systems suffer significant sample dilution. Further, while commercial IRMS systems are available for measuring CO2 isotopic differences, conventional optical cavity architectures currently require more than ˜100 nanomoles of CO2 to be effective. The technical literature reports best case minimum detectable absorbance (MDA) values for continuous-wave-QC laser systems used in concert with compact IR cavity ring down spectroscopies of about 2.2×10−8. Furthermore, while IR absorption in multi-pass or ring-down optical gas cells has been applied to stable isotope measurements, only a fraction of a sample can be ablated by the laser and released into the multi-pass or ring-down cavity in these systems. Given that analyses in these systems require about 200 to 300 nanomoles of sample, isotopic imaging at a 1 micron resolution is precluded. Secondary Ion Mass Spectrometry (SIMS) can also provide data similar to those obtained with laser ablation, but at a cost that is at least ten times greater and a throughput that is lower. SIMS also requires substantial sample preparation and must be performed under ultra-high (e.g., 10−7 Torr or less) vacuum conditions, which have the potential to alter the sample, and further precludes any in vivo studies. Accordingly new systems, devices, and processes are needed that enable determination of stable isotopes at the single cell level or better. The present invention addresses these needs.